WD-DataLink-1.0

[Laurent Michel]

Hello Path,

Thank for the job.

There are several questions or suggestions  I would to talk about.
==================================================================

1.2.4: Standards Services:
If the client is supposed to know the parameters required by the service, it does not know their range for a given observation. 
  We could say here more clearly  that the client must use its own data discovery capabilities (DM knowledge, UCD parsing...) to 
get them.

1.2.5: Free or Custom Services
I think that you could mention here the use-cases we developed in our note published last spring. This not could also be put in 
the paper references.

2.1.1 REQUEST
Could you give some example of a REQUEST parameter "value triggering alternate behaviour"
Is that the way you suggest for custom services to deliver their parameter descriptions?

2.1.3 ID
"the service will return at least one... " Why put this particular caveat on the number of links returned by the server. An 
empty list can be returned for dataset without available links (e.g. no available progenitors).

4 List if Links:
AccessURL/ErrorMessage on required/one empty. I think that the spec must be a bit more flexible to support services not 
perfectly compliant: If the ErrorMsg is not empty, then the AccessURL is ignored. So, the client knows what to do even when both 
field are set.

4.4 Service Type
I would be nice to add a table listing all Service TAP

And one 2 fundamental issues
============================

Registry: According to your documents, the client has to get a query response before to know whether the datalink is supported. 
That makes senses in most cases. But it would nice to propose a way to mention somewhere in the registry capabilities whether a 
service support Datalink  or not.

Self described service: There is almost nothing a bout the self described service and especially about how parameters are 
described. They are just mentioned. I do believe, though, that this feature is very important and not only for my own services 
since that is the way to connect the VO to legacy web services.


Cheers
Laurent


Le 25/10/2013 19:40, Patrick Dowler a écrit :
>
> The first official and more or less complete WD for DataLink is now available in the document repository (in the Documents in
> Progress section).
>
> Direct link is here:
>
> http://www.ivoa.net/documents/DataLink/index.html
>
> There are some possible re-organisation necessary (sec 2 and 4 go together and sec 3 needs to move to either before or after
> them). Also, the allowed values in the "semantics" column are still a bit up in the air and the ones presented are not final. I
> thought it better to get this out now.
>
> PS-Thaks to the co-authors and participants at the last couple of interop meetings for their contributions - it all helped to
> bring this together into what I hope is a simple and concise document.
>

-- 

---- Laurent MICHEL              Tel  (33 0) 3 68 85 24 37
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